Proportional fluid feeding device



Aug. 11, 1936. E. E. EDWARDS ET AL PROPORTIONAL FLUID FEEDING DEVICEFiled Nov. 19, 1934 2 Sheets-Sheet l fnrjeniors f/ared f. EaWar 5 JosephE Pu/nam Patented Aug. ill, rare L ATNT PRGPORTIONAL FLlUllD FEEDINGDEVICE Application November 19, 1934, Serial No. 753,522

Claims.

This invention relates to fluid feeding devices, and particularly tothose which are adapted to control the rate of flow of a liquid inproportion to the rate of flow of a fluid, 'such as a confined flowingstream of gas.

In the natural gas industry the problem has arisen of introducing anodorant material, usually a volatile liquid, into the normally odorlessgas, so as to give the latter a distinct and easily recognizable odor,to reveal the presence of leaks, accidentally extinguished-burners, andthe like. In order to accomplish this safely and econom ically, theratio of odorant to gas volume should be kept at a constant value. Thegas is usually confined in a pipe or conduit at a pressure which mayrange from substantially atmospheric pressure to one of several hundredpounds per square inch. Rates of flow may be extremely variable, rangingfrom a minimum early in the morning to several maxima, of variousmagnitudes, during different parts of the day.

Heretofore, apparatus for this purpose have involved intricate andcomplicated systems of dia== phragrns, linkages, throttle valves, pilotvalves, pumps, overflow weirs and the like, all of which are more orless unreliable without constant attention and many of which are subjectto corrosion by the liquid being handled. In addition many require theuse of a supplementary power supply, which is not always available, andwhich constitutes a source of continued expense in addition to the highinitial cost of such devices.

It is an object of this invention to provide a sensitive diiferentialfluid pressure responsive device which is adapted to operate upon largeor small pressure differentials, which has a minimum of moving parts andwhich is also adapted to magnify small changes in pressure differentialto actuate directly 2. positive liquid flow control means, the latteradapted to introduce the said liquid into the fluid stream or to disposeof it in any other manner.

Another object is to provide a device of this type which is entirelyself-contained and which requires no outside power supply for itscontinued operation.

Another object is to provide a device of this type which willautomatically stop the liquid being 'fed upon the cessation of flow ofthe fluid producing the pressure difierential, and will resume operationupon a starting of the flow of the latter fluid.

Another object is to provide an automatic device that will introducevolatile odorant liquid into a confined moving stream of gas at a rateproportional to the rate of flow of the latter.

Another object is to provide an odorant feeding or metering device thatwill require substantially no alteration to the gas line to which it isattached, and which will ofier little or no restriction to the normalflow of gas in said line.

Another object is to provide an odorant feeding or metering device thatmay be easily altered to make changes in the desired proportion ofodorant liquid to gas flow rates, or to changes in the characteristicsof the gas ilow.

These and other objects and advantages will become apparent from thedescription which follows and from the accompanying drawings, which forma part of this specification and illustrate a preferred embodiment ofthe invention, as applied to an odorant feeding device for a natural gasline.

In the drawings- Figure 1 is a vertical sectional view on the lon=gitudinal axis of an odorant feeding device in place on a gas line.

Figure 2 is a horizontal sectional view on line II-H of the device shownin Figure 1, and

illustrates the float arm, hinge, float, and counterweight in place inthe odorant tank.

Figure 3 is a vertical sectional view on line III-III of Figure 2, to anenlarged scale and illustrates one form of construction of the float armhinge.

Figure 4 is a vertical sectional view on line IV-IV of Figure 1, also toan enlarged scale and illustrates a preferred construction of the floatelement in which the liquid feeding orifice is mounted.

Referring to the drawings and particularly to Figure l, the numeral itrepresents a tight steel tank in which the volatile odorant liquid H maybe stored, and which also serves as an enclosure for the controlmechanism. Tank i0 is preferably mounted upon any suitable support (notshown) above the gas pipe line i2 into which the odorant liquid is to bemetered.

In order to obtain a. pressure diflerential proportional to the velocityand 'therefore the rate of gas flow in line it, two Pitot tubesgenerally designated i3 and it, are provided, each of which is composedof a closed tube l5-lti with a side opening lil8. Opening ll faces thegas flow in line l2, as indicated by the arrow, which flow causes avelocity head pressure to be imposed upon the normal line pressure orstatic pressure in Pitot tube l3. Opening i8 is illustrated as facingdown stream and is thereby subject to static pressure minus the velocityhead pressure. If desired, tube it could be made responsive only tostatic pressure by being made open ended.

Tubes l3 and it will hereafter be referred to as the high pressure andlow pressure Pitot tubes,

respectively. They may be suitably mounted in the screwed nipples l9Welded to line l2, and are provided with any conventional orientingmeans or indicia so that the position of the openings ill-48, withrespect to the longitudinal axis oi connection 2| is also preferablyprovided with a flanged union 24 near its junction with the bottom ofthe shell of tank In. High pressure connection 20 leads to the top oftank l0, where it is connected to dome 25, on which cover plate 26 andgasket 21 may be secured by bolts 28. Dome 25 also forms a space intowhich the float mechanism, to be described below, may be accommodated,as shown by the dotted lines of Figure 1,

r as when the tank I is first filled with odorant liquid N. A gage glass29 of the conventional type may be provided to indicate the liquid levelin tank l0.

The juncture-between the low pressure con nection 2|, which leads fromlow pressure Pitot tube l4, and tank I0, is conveniently made by anipple 30 which extends from flanged union 24 and is preferably weldedinto the tank shell Ill. Supported on the inner end of nipple 30 insideof tank l0 (Figure 3) is a hinge body 3|. Hinge pin 32 is pivotallysecured in the latter between the seat 33 and the center pivot '34,which latter is urged into recess 35 in pin 32 by spring 35. A cap 31secured by screws 38 provides for removal and dismantling of the hingeassembly. These parts are preferably made from corrosion resistingalloys, such as brass or stainless steel, and the particular arrangementshown in this example has proved to work with a minimum of friction.

It will be noted that the low pressure connection nipple 30 is threadedas at 39 into a passage 40 in hinge body 3|, which passage communicatesthrough seat 33 with the passage 4| in hinge pin 32. Float arm 42 isthreaded into hinge pin 32 at right angles to the axis of rotation ofthe latter and is also provided with a central bore 43 whichcommunicates with passage 4| and leads to the float assembly generallydesignated 44. A counterweight 45 is threaded onto rod 46, which extendsfrom hinge pin 32 in the opposite direction from float arm 42, andserves to balance the float assembly 44 as will be described below:

Float assembly 44 is best shown in Figures 1 and 4, and consists of anupright displacement cup 41, to the bottom of which is connected floatarm 42, so that any liquid which may enter the cup will drain throughbore 43 in arm 42 and thence through the hollow hinge assembly, lowpressure connection 2|, and eventually into gas line l2. A limit stop 48is preferably securedinside tank Hi to prevent float arm 42 fromreaching a horizontal or downwardly inclined position relative to theaxis ofthe hinge pin 32, so that liquid may always flow therethrough asjust described.

Near the bottom of displacement cup 41 is mounted a flange 49, which maybe soldered to the cup wall, and into which may be screwed a threadedplug 50, provided with an orifice Displacement cup 41 is also flttedwith one or more vent openings 52 near its upper edge for a purposewhich will be described below.

Surrounding cup 41, is a float or cover shell 53 which is open at thebottom. The closed top of shell 53 is preferably provided with centeringclips 54 and the shell may be detachably secured to cup 4'|'by means ofa. wire bail 55 which passes through holes 56 near the bottom of theskirt of 5 cover shell 53 and clamps over a clip 51 on the bottom offloat arm 42 near its outer end. This provides an easy means forsubstituting another shell of difierent diameter, in case thecharacteristics of the device are to be altered, as will be dscribedbelow. 1

The design of float shell 53, cup 41 and the location and size oforifice opening 5| are obviously dependent upon the maximum velocity ofgas flow in line l2, the flow characteristics of the odorant liquid andthe ratio between the volume of gas and odorant material that it isdesired to maintain. Factors bearing upon these values will be discussedbelow and a concrete example given, from which the design of otherinstallations may readily be determined by one skilled in the art.

The velocity head pressure is imposed upon Pitot tube l3 and is carriedthrough high pressure pipe connection 20 to tank ||l above the liquidlevel therein. The low pressure is communicated from line |2 throughPitot tube l4 and connection 2| hinge assembly and hollow float arm 42tothe interior of cup 41, from which it communicates through vent 52into the inside of float shell 53. The top or outer side of shell 53 istherefore subject to a higher pressure over its entire crosssectionalarea, than that inside the shell, causing the latter to sink in theliquid N, until the added displacement of cup 41 over itscross-sectional area, balances this downward force. Float assembly 44 isoriginally balanced by counterweight 45, so that it will float in theliquid N with orifice 5| just above the liquid level in the annularspace between cup 41 and float shell 53.

It is obvious that the only force acting to depress float assembly 44 isthe pressure differential communicated to the opposite sides thereof byPitot tubes i 3 and I4 or their equivalent. This force will beproportional to the velocity and therefore the rate of gas flow, andwill act directly upon the orifice 5| to move the latter below thesurface of the liquid ii, causing proportional flow of the liquidthrough arm 42, hinge 3|, connection 2| and tube l6 into line 2, asoutlined above. If desired, the liquid N may be trapped or diverted fromline |2 to any other destination, if such were the object of the device.

If a considerable pressure differential is available, as would be thecase of an orifice in a high pressure line, where a relatively highpressure drop would not be objectionable, there would'be acorrespondingly greater force available to push the float assembly 44downwardly into the liquid. In this case, to prevent too greatsubmergence of 60 orifice 5|, or in effect, to decrease the sensitivityof the feeding means, the respective cross-sectional areas of floatshell 53 and displacement cup 41 would be approximately the same, sothat a strong downward force on the exposed area 01' 65 the top of shell53 would be counterbalanced by a relatively strong buoyant forceupwardly from the effective cross-sectional area of the displacement cup41 in liquid N. If, however, there is only a slight differentialpressure available, as in 7 the case of a large, low pressure gas linewith Pitot tubes as shown in Figure 1, the cover shell 53 should berelatively much larger in cross-sec tional area than displacement cup41, so that the latter would sink deeply with but a slight in- 7 creasein differential pressure in the exposed area of shell 53. Thus, thesensitivity of the liquid feeding means varies as the ratio of thecrosssectional areas of the shell 58 and the cup 41.

Should the absolute pressure in conduit I! change due to varying load orfor other reasons. the resulting change in density of gas in the conduit will cause a variation in the pressure diflerential which controlsthe submergence of orifice 5|. This will substantially compensate forthe pressure-volume change in the 'gas and will tend to preserve theproportional rate of flow of liquid I I from tank It).

It has been found that for small liquid flows through orifice 5| thereis a practical minimum diameter which should be maintained, for if toosmall an orifice is used the well-known Reynolds number" will be toosmall to give a reliable flow discharge coeflicient and unsteady flowwill result. with an odorant material such as Calodorant, a. petroleumderivative having substantially the flow characteristics of a lightgasoline, a minimum orifice diameter of 0.031 inch was found desirable.i

In practice, for an installation on a 10 inch gas line operating at 100lbs. per sq. inch and having a maximum demandrate of 100,000 cubic feetper hour, to which odorant was to be added at the rate of 3 gallons permillion cubic feet, the orifice diameter was determined to be 0.035inch, with a maximum submergence of 2 inches. The displacement cup 41was 3 inches in diameter, and the cover shell was 17 inches in diameter.The tank size is obviously immaterial, being determined by convenienceand storage capacity desired.

It will be appreciated, that, from the foregoing description andexample, one skilled in the art of hydraulics will be able to adapt thisinvention to any given set of conditions of gas flow, pressure,

and proportion of odorant to gas flow. The es-- sential feature of theinvention appears to reside in the combination of a diiferentialpressure actuated flpat, carrying flow control means responsive to theposition of the said float in a liquid supply, to cause a flow of thelatter in proportion to the fluid flow producing the said pressuredifferential. Although a specific construction embodying this inventionhas been described and illustrated, it is to be understood that theinvention is not limited to that specific device, and all suchmodifications and changes as come within the scope of the appendedclaims are embraced thereby.

We claim:

1. ma liquid flow control apparatus, the combination of a conduit, meansin said conduit for creating a pressure differential proportional tofluid flow therein, a closed liquid storage tank, a

being responsive to the pressure differential in said conduit to varythe flow of liquid through said orifice.

2. A liquid flow control apparatus according to claim 1, in which saidfloat is carried by a hinged member, said member provided with a passagethrough which liquid entering said float through said orifice will flowout of said tank.

from said-tank into said gas line,'at a rate pro- 3. A liquid flowcontrol apparatus according to claim 1, in which'said float is carriedby a hinged 1 member, by means of which liquid entering said floatthrough said orifice will flow to said static pressure connection, andthence into said conduit. 5

4. A liquid fiow control apparatus according to claim 1, inwhich saidfloat is provided with an outer shell and an inner cup, the outer shellopening downwardly and the inner cup opening upwardly, the said orificebeing in the wall of said inner cup, and adapted to be submerged belowthe liquid in the annular space between said cup and said shell.

5. In a liquid flow control apparatus of the type described, a movablefloat in a closed liquid storage tank, said float comprising a hollowchamber in communication with and sealed by the liquid in. said tank,saidtank and said float chamber being connected, respectively, tosources of high and low differential pressure, oi liquid flow control 20means carried by said float and responsive to its position in the saidliquid, and conduit means leading from said flow control means toconduct the said liquid to a point outside of said tank at a rateproportional to said pressure differential. 2 6. A liquid flow controlapparatus according to claim 5, in which said liquid flow control meansincludes an orifice adapted to be submerged with said float by thedifl'erential pressure acting thereon, to permit liquid to flow fromsaid tank. 30 7. In an apparatus for introducing an odorant liquid intoa confined flowing stream of gas in a conduit; the combination of aclosed odorant storage tank mounted above said gas conduit, a Pitot tubein said conduit with its opening facing 35 the flow of gas therein, asecond conduit connecting said Pitot tube with the space above theliquid in said tank, a float in said tank, said float comprising ahollow chamber in communication with and sealed by the liquid in saidtank, a third conduit connecting the interior of said float with saidgas conduit, and liquid flow control means carried by said float andcommunicating with said third named conduit to permit odorant to flow 45portional to the gas flow therein.

8. A float for a liquid flow control apparatus of the type described,comprising an outer shell having a closed top and open at the bottom, aninner cup closed at the bottom and mounted in said outer shell, meansforming a gas passage between said shell andsaid cup at their upperends, means for fastening said shells together, and an orifice in saidinner cup. a

9. In a liquid flow control apparatus, the combination of a conduit,means in said conduit for creating a pressure differential proportionalto fluid flow therein, a closed liquid storage tank, a movable float insaid tank, means forming a high pressure connection from said pressuredifl'erential means to the tank above the liquid level therein, meansforming a low pressure connection from said pressure differential meansto said float, and flow control means carried by said float to conductsaid liquid from said tank, the position of said 65 float with respectto the liquid level in said tank being responsive to the pressuredifferential in said conduit to vary the flow of liquid through saidflow control means.

,10. A liquid flow control apparatus according to claim 9 in which saidfloat comprises a hollow chamber in communication with and sealed by theliquid in said tank.

ELDRED E. EDWARDS.

JOSEPH F. PUTNAM. I5

